Looking for a hot water add on

Whats up guys im looking into getting some hot water so we can take care of some pesky oil stains on dumpster pads and such. We havent had much use for heat on any residential jobs so this will be strictly for commercial use so buying a whole unit seems silly. Ive been looking into the north star add on heaters then mounting it in one of the trailers and bringing it along when needed. Does anybody have any experience with these? Any recommendations? We are using 2 pressure pro washers right now.

I don’t have any experience with hot water systems, but I’d skip NT and start my search here:

http://pressuretek.com/hotboxs.html

Or here:

https://www.powerwashstore.com/C/231/Hot-2-Go

You will get much better support and quality from one of those vendors.